The currentTime property should be more granular than seconds. Do you not see this? In fact, it should be really granular, but we only dispatch currentTimeChange events every 250 milli-seconds by default. I did a quick test, and when polling this property on every frame, it gets updated correctly.

In the VideoPlayer, in the UI, we round to the nearest second, though one could change that by modifying the skin or overriding formatTimeValue() in VideoPlayer.